Vol 484, No 6 (2019)

The system of pressureless gas dynamics is a hydrodynamically justified generalization of the system consisting of the Burgers vector equation in the limit of vanishing viscosity and the mass conservation law. The latter system of equations was intensively used, in particular, in astrophysics to describe the large scale structure of the Universe. The solutions of the vector Burgers equation involve interesting dynamics of singularities, which can describe concentration processes. However, this dynamics does not satisfy the law of momentum conservation, which prevents us from treating it as dynamics of material objects. In this paper, momentum-conserving dynamics of singularities is investigated on the basis of the pressureless gas dynamics system. Such dynamics turns out to be more diverse and complex, but it is also possible to formulate a variational approach, for which the basic principles and relations are obtained in the work.

The first mixed problem for the Vlasov-Poisson system in an infinite cylinder is considered. This problem describes the kinetics of charged particles in a high-temperature two-component plasma under an external magnetic field. For an arbitrary electric field potential and a sufficiently strong external magnetic field, it is shown that the characteristics of the Vlasov equations do not reach the boundary of the cylinder. It is proved that the Vlasov-Poisson system with ion and electron distribution density functions supported at some distance from the cylinder boundary has a unique classical solution.

A closed-form solution is proposed for the problem of minimizing a functional consisting of two terms measuring mean-square distances for visually associated characteristic points on an image and meansquare distances for point clouds in terms of a point-to-plane metric. An accurate method for reconstructing three-dimensional dynamic environment is presented, and the properties of closed-form solutions are described. The proposed approach improves the accuracy and convergence of reconstruction methods for complex and large-scale scenes.

Amorphous alloys Fe_85-xCr_xB₁₅ (x = 0-20), prepared by rapid quenching of the melt, have been studied by pulsed nuclear magnetic resonance (NMR) on nuclei ¹¹B at a temperature of 4,2 K. The amorphous alloys consist of nanoclusters with short-range order of the tetragonal t-(Fe, Cr)₃B and α-(Fe, Cr) phases which contain chromium atoms in the nearest surroundings of boron atoms. The average magnetic moments of magnetic atoms in the nearest sphere of boron atoms in nanoclusters and their dependence on the chromium content in alloys are estimated.

The results of analyzing the long-term variations in the strain rate of a TiNi element during martensitic transformation cycling have been reported. It is shown that the factors involved in the formation of the state of the environment lead to unstable operation of functional technical elements similar to those based on titanium nickelide.

The limitations imposed on the orbit and the distribution of the density of the early Moon by present-day measurements of its fossil tidal bulge are studied. A semi-analytical method has been developed for calculating gravitational potentials, which makes it possible to investigate the equi-potential surfaces of a self gravitating inhomogeneous mass in an external field. Universal expressions are obtained for the two-layer mantle-crust model of the early Moon, which makes it possible to make general estimates of the density of the upper crust and semiaxes of its orbit in the case of tidal capture by the Earth.

The results of investigation of the carbonate system parameters dynamics in the middle and lower reaches of the Ob River in July 2016 were analyzed. The distributions of the carbonate characteristics of the river waters were found to follow a steady latitudinal trend determined by the landscape-geochemical conditions of the drainage basin and by the permafrost distribution. The first field data on the magnitude and direction of the CO₂ fluxes in the river water-atmosphere system in this region were presented. It was shown that the waters in the middle and lower reaches of the river are multiply supersaturated with CO₂ with respect to its atmospheric content, and the daily average evasion reaches 625,9 mmol m^-2 day^-1 at an average value of 102,1 mmol m^-2 day^-1. It was determined that the waters of the Ob River in the studied reaches are a significant CO2 source to the atmosphere; according to conservative estimates, the total flux in July was 2 ⋅ 10¹¹ g of carbon in the form of CO₂.

The electrospray method was used for the first time to prepare polymeric capsules from bioresorbable dl-lactide and glycolide copolymer loaded with biological molecules from the cell secretome and, in particular, human interferon a-2b (IFN a-2b). The obtained nearly spherical submicron capsules were studied by scanning electron and confocal laser microscopy. The capsules retain the structural integrity and the cytotoxic activity of IFN a-2b towards tumor cells. The electrospray method is distinguished by high adaptability and environmental safety and is suitable for manufacture of a broad range of materials with different composition and morphology promising for the targeted delivery of drugs and biological molecules.

ZrO₂–Y₂O₃ nanostructured systems with different yttria content (Y₂O₃ = 0, 3 and 10 mol.%) were synthesized under hydrothermal conditions and their structural, optical and electronic properties were investigated. Using ZrO₂–Y₂O₃ systems the electron-conductive thin-film photoelectrodes were fabricated and used to develop the perovskite solar cells (PSCs) with the device configuration glass/FTO/ZrO₂-Y₂O₃/CH₃NH₃PbI₃/spiro-MeOTAD/ Au. The comparative studies of the PSCs photovoltaic parameters revealed that under 1000 W/m² (AM1.5G) illumination solar cells with ZrO₂–Y₂O₃ photoelectrodes demonstrated considerably higher power conversion efficiency in comparison with PSCs based on the undoped ZrO₂ photoelectrodes.

Typical features of platinum group minerals (PGMs) and the results of ¹⁹⁰Pt–⁴He dating of the Fe–Pt solid solutions are presented for complex gold–platinum–diamond placers with unidentified sources of the Anabar River basin. For the first time, the ¹⁹⁰Pt–⁴He isotopic system is used for determination of the possible age of the primary source of a PGM placer from the example of ferroan platinum with a disordered structure along with isoferro- platinum. The PGMs of these placers mostly include ferroan platinum and isoferroplatinum and rare Ru–Ir–Os alloys. The calculated bulk composition of the silicate inclusion of Ir platinum corresponds to the rocks of the ijolite–melteigite series. The ¹⁹⁰Pt–⁴He age of the Fe–Pt solid solution grains is 261 ± 13 Ma. Thus, our data indicate the relation between placer PGMs of the Anabar River basin and Permian-Triassic complexes of alkaline-ultramafic rocks.

The Sr-isotope composition of the Central Azov Group carbonates (0.70322-0.70352) and Nd model age of silicate sediments (2.34-2.31 Ga) has been reported. The U-Pb age of trondhjemite (2052+5 Ma) cutting the carbonates has been determined. According to the obtained data, the marine sedimentary cover of the Azov block making up the Early Precambrian Sarmatia Continent emplaced in the Early Paleoproterozoic at 2.23-2.34 Ga.

The results of studies indicate that the age of the protoliths of garnet-bearing biotite–sericite–muscovite schists of the Inim Block is <991 Ma, and they are derived from rocks of the Neo-, Meso-, and Paleoproterozoic (as well as Archean) crust. This suggests that the Inim Block is exotic relatively to the Argun Superterrane due to the formation of the protolith of its metasedimentary rocks largely from erosion products of the Early Precambrian continental crust, the presence of which within the Argun Superterrane is not proven. It is not excluded that the Inim Block is a fragment of the Dzhugdzhur–Stanovoi Superterrane implanted in the structure of the Argun Superterrane as a result of Mesozoic tectonic events.

The petrogeochemical characteristics of high-pressure mafic tectonites from the Yenisei suture zone of Yenisei Ridge indicate that N-MORB and E-MORB with an age of 701.6 ± 8.4 Ma were their protolith. The formation of N-MORB with the more primitive chemical composition occurred at the initial stages of spreading, when the upper horizons of the depleted mantle were molten. The high-Ti basalt was formed as the product of melting of the enriched mantle substrate at the later stages of spreading. These events are related to the early stage in the evolution of the Paleo-Asian Ocean on the western margin of the Siberian Craton.

The results of comparing the data of two methods of geophysical monitoring of the stress-strain state of a borehole of the geoenvironment in the zone of Petropavlovsk-Kamchatsky geodynamic testing site to the data on the focal mechanisms of earthquakes that occurred in this zone on the same time interval are presented.

Article presents a new approach to the analysis of spectrometric data obtained by modern spectrometers in the visible range of wavelengths for surveys of surface water bodies. The efficiency of the new approach in the interpretation of spectrometric data in the visible range is shown with the use, proposed by us, of the space of optical images (SOI) formed by a combination of experimental and model ranges of the remote sensing reflectance (RS). The RS ranges calculated parallel to measuring the absorbance indexes in particular hydrological seasons with a known structural composition of phytoplankton permit us to gradate the SOI with respect to the structural composition of phytoplankton. The curve of the status of the ecosystem of the Don River constructed by the data of remote spectrometry shows changes in the structure of phytoplankton during the observation period.

The features of vortical suppression of tsunami waves by an impermeable underwater barrier have been studied. The height of the barrier is close to the optimum corresponding to the maximum effect of vortical suppression of the wave energy. It is shown that the energy of suppressing tsunami waves by such a barrier depends on the wave height and can vary from zero to 80% of the incident wave energy.

The thienopyrimidine derivative TP03 (a low molecular weight agonist of the luteinizing hormone receptor, LHR), when administered to male Wistar rats, stimulated the production of testosterone (“T”), elevated level of which was maintained for 7 days, and increased the expression of the LHR gene. At the same time, the steroidogenic effect of human chorionic gonadotropin (hCG), which significantly increased the “T” level on the first day of treatment, was further weakened, which was accompanied by a decrease in the expression of the LHR gene in the testes, indicating the development of resistance of Leydig cells to hCG. In the testes, the hCG treatment induced a compensatory increase in the expression of genes of the steroidogenic enzymes, such as the cytochrome P450_scc and the dehydrogenase 3P-HSD. In the case of TP03 treatment this effect was absent.

The biofilm formation by bacteria E. coli is a magnetosensitive process. The combined effects of a magnetic magnesium isotope ²⁵Mg and a static magnetic field in the range of 20-35 mT stimulate biofilm formation by bacteria E. coli compared to non-magnetic magnesium isotopes ^24,26Mg. Magnetic field effects in the range of 2-10 mT, registered for all bacteria regardless of magnesium-isotope enrichment of nutrient medium, indicate the sensitivity of intracellular processes to weak magnetic fields.

Tag7 (PGRP-S) is an innate immune protein that is involved in the antibacterial and antitumor defense and stimulates the maturation of cytotoxic lymphocyte subpopulations. It was found that the incubation of lymphocytes with Tag7 for 3 days promotes the appearance of cytotoxic NK cells that are active against a number of tumor cell lines.

A model of weak viability selection at two multi-allele loci with standardization of approaches through the use of perturbation theory is examined. The estimate of the quasi-equilibrium value for the linkage disequilibrium coefficient D is analyzed, and results in terms of average effects in quantitative genetics and in terms of the theory of singular perturbations in mathematics are obtained. The approximation of a discrete-time model of a random mating population with non-overlapping generations under weak selection by ordinary differential equations is considered. Weak selection is considered as a perturbation of the model without selection. The resulting model is singularly perturbed; that is, fast (D) and slow (allele frequencies) variables can be distinguished. The first approximation equation for quasi-equilibrium of D is obtained using the first terms of the Taylor series expansion of the model functions. It coincides with the corresponding part of the system of the first approximation of the asymptotic series for solving singularly perturbed equations.